52V / BBS / Smart chargers

Hub producer advice: 12 mosfet is the key point. 9 mosfet controller may have problems, not recommend to use 52V battery. The controller for 350W is just 6 mosfet, even the 9 mosfet controller get hot. BBSHD maybe is using 12 mosfet, 52V will work well with hub engines+12 mosfet controllers.
MJ170cells
Is It Wise To Power My 48 Volt Mid Drive System With A 52 Volt Battery? The BBS02 and BBSHD drive unit controllers can take a range of voltages from a low of 39v to a high of 60v, but there is no question that these units perform much better at the higher end of that range. A 52v battery fresh off the charger at 59v is a peppy wheelie machine, while on a 48v battery when the voltage drops below about 44v starts to feel pretty anemic. It is my belief that these mid drives were actually designed from the ground up to work with 52v packs. In China, it is not uncommon to buy a 48v labeled pack that is really a 52v pack, so the folks at Bafang had to design for that contingency. Now that Bafang has upgraded the controller mosfets, the weak point on both the BBS02 and the BBSHD is the nylon primary reduction gear . When the BBSHD was hooked up to a 65 Amp Lyen controller the nylon gear was the first thing to melt. Luckily the nylon gear is only about $20 to replace and it takes about an hour for a BBS veteran to swap out.
Do you really feel a difference when riding with a 52v battery instead of a 48v battery? I have spent hundreds of hours riding the BBS02 & the BBSHD with both 52v and 48v batteries from a variety of vendors. Honestly, right off the charger both the 48v and the 52v batteries feel about the same even though the 52v battery is about 4v more. I have not noticed any difference in the top RPM range of the unit, although it might be slightly higher with a 52v pack. The real differences come when your ride is about 1/2 over. With a 48v battery, once your battery is about half depleted you can feel the power drop off slightly. As the battery gets down to about 1/4 of its charge left, the difference becomes even more noticeable with both throttle lag and a noticeable lack of power. With a 52v battery this never really happens as the voltage never sags into the ‘ho-hum’ zone. With a 52v battery the BBSxx drive units run quite powerfully right up until the battery BMS cuts out.
The BBSHD is an animal of another color. The BBSHD seems to run just fine all day long at 30 Amps and with a 52v pack. This motor system was so overbuilt that I honestly have a hard time believing that you are going to have any problems with this unit using a 52v battery over a 48v battery. The controller has 12 mosfets instead of 9 with the 750W BBS02 and there are large cooling fins on both the motor and the controller. I’ve hooked up a temperature probe on my BBSHD and the thing barely gets hot even when climbing extended hills at full throttle. Try that on a BBS02 and you will most likely have a serious problem.
Overall the voltage of the battery you’re using is not as important as having the right sized chainring for the application. If you are trail riding, you will not want to use the large 46T steel chainring with the BBSHD or the 48T chainring with the BBS02.
Overall the voltage of the battery you’re using is not as important as having the right sized chainring for the application. If you are trail riding, you will not want to use the large 46T steel chainring with the BBSHD or the 48T chainring with the BBS02. I find that the 42T Luna eclipse or the 42T Lekkie Bling Ring work pretty well for both trail riding and commuting. If you have a cargo bike or a tandem then a 30T Luna Mighty Mini is a decent choice, but I think it produces a little too much torque for the trails. On the BBS02 for trail riding, you will want a 38T or smaller chainring, I highly recommend the 30T Luna Mighty Mini for the BBS02. This is by far my favorite BBS02 chainring and it will help save your plastic gear and your controller when you are running with a 52v battery. The average size of chainring on my BBS02 builds is 34T and I have had great luck with both the 34T and the 36T Raceface rings with an adapter.
If you are running a hub motor and want to decide between a 48v and 52v battery I’d say just go with the 52v battery. Most quality controllers will be able to take the extra power and it should give you a few more mph of top speed. In general, if you want more torque you add amps, if you want a higher top speed then you add volts. When you add amps you have to make sure that your phase wires are thick enough and that the controllers have enough solder on the boards to carry the loads. When you add volts you really only have to worry about frying your mosfets in the controller.
Unboxing EM3ev 52v 14s 6p 19Ah premium triangle battery from Paul – Electric Bike
smartSmart charger can charge @  1-5 amps, 80% 90% or 100% for longer battery lifesatiator-detailsgoph
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